Lube oil pump design

ABSTRACT

A rotary pump for pumping liquids includes a motor, a shaft that is driven by the motor, an impeller that is attached to the shaft, a rolling element bearing that surrounds the shaft and a bearing housing for the rolling element bearing. The bearing housing defines a lubricant reservoir in a volume of the bearing housing not occupied by the rolling element bearing. The rotary pump can also include a conduit in communication with the bearing housing and a grease cup fitting in communication with the conduit. The motor can rest on a motor support and the grease cup fitting can be easily accessible by locating the fitting outside of a peripheral side wall of the motor support.

This application claims the benefit of Provisional Patent Application Ser. No. 60/605,661, filed Aug. 30, 2004, entitled “Lube Oil Pump Design,” which is incorporated by reference.

BACKGROUND OF THE INVENTION

Vertical liquid medium pump systems are known, an example of such a pump is disclosed in U.S. Pat. No. 6,315,530 and Buffalo Pumps Bulletin 986, entitled “Lube Oil Pumps,” each of which is incorporated by reference. These known pumps are typically used to transport lube oil. Components of the pump are submerged in a reservoir of lube oil and the pump transports the lube oil to a desired location.

In these known pumps a rolling element bearing supports a main pump shaft and a sealed bearing housing contains the rolling element bearing. The rolling element bearing is lubricated using grease and after a period of operation requires re-lubrication. Re-lubrication of the rolling element bearing in the known pump requires removal of the pump from the reservoir of lube oil and disassembly of the major pump components. This activity is time consuming and complex.

SUMMARY OF THE INVENTION

A rotary pump for pumping liquids includes a motor, a shaft that is driven by the motor, an impeller that is attached to the shaft, a rolling element bearing that surrounds the shaft and a bearing housing for the rolling element bearing. The bearing housing defines a lubricant reservoir in a volume of the bearing housing not occupied by the rolling element bearing. The rotary pump can also include a conduit in communication with the bearing housing and a grease cup fitting in communication with the conduit. The motor can rest on a motor support and the grease cup fitting can be easily accessible by locating the fitting outside of a peripheral side wall of the motor support.

The lubricant reservoir in the bearing housing can have a volume great enough to store spent lubricant used to lubricate the rolling element bearing. In one embodiment, the lubricant reservoir can have a volume greater than 2.25 cubic inches. In another embodiment, the lubricant reservoir can have a volume greater than 5 cubic inches. The lubricant reservoir can also have a volume less than 12 cubic inches. The shape of the lubricant reservoir can take many different configurations, including a cylindrical cavity, a frustoconical cavity, a rectangular cavity, a polygonal cavity, as wells as other configurations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view, partially in cross-section, of a rotary pump.

FIG. 2 is a close-up view, partially in cross-section, of an upper portion of the rotary pump of FIG. 1.

FIG. 3 is a close-up view similar to FIG. 2 of a known rotary pump.

DETAILED DESCRIPTION OF THE INVENTION

A new rotary pump will be described in comparison to a known rotary pump, however the invention is not limited to simply an improvement over the described known rotary pump. The invention can be used in other environments and with other rotary pumps. For ease of understanding the differences between the known rotary pump and the new rotary pump, the figure numbers of the known pump will correspond to the reference numbers of the new pump, except that the reference numbers for the known pump are increased by one hundred.

With reference to FIG. 1, a rotary pump 10 includes a motor support 12 that supports a motor 14 (depicted schematically). The motor 14 drives an elongated generally cylindrical pump shaft 16 that connects to an impeller 18. The pump shaft 16 can have different diameters along its length. The lower portion of the pump 10 is placed in a reservoir 20 of liquid, typically lube oil, to be transported or pumped. The motor support 12 mounts on a rigid cover plate 22 and includes peripheral side wall 24 having openings 26. A connecting column 28 attaches to and extends from the cover plate 22 to surround the shaft 16. The connecting column 28 also attaches to a casing cover 32, which in combination with the casing 34 provides a housing for the impeller. Liquid enters the casing 34 through a lower inlet 36 where it passes through the impeller 18 en route to a discharge pipe assembly 40. These components are also found on a known rotary pump.

FIG. 3 discloses an upper section of a known pump 110 where a rolling element bearing 138 supports the pump shaft 116, similar to the pump shaft 16 described above. The bearing 138 surrounds the circumference of the pump shaft 116. An end of the connecting column 128 adjacent the cover plate 122 includes a stepped cylindrical cavity 142 that is concentric with the pump shaft 116. The cavity 142 can be described as stepped in that the cavity includes an upper vertical side wall 144 that abuts and/or bears against a radial side wall 146 of the bearing 138 and a horizontal ledge 148 formed at a lower end of the upper side wall 144. A lower annular wall 152 of the bearing 138 rests on and/or bears against the ledge 148. A lower vertical side wall 154 extends between the ledge 148 and a horizontal base wall 156 of the cavity 142. A gasket or lip seal 158 surrounds the pump shaft 116 and is provided to seal the cavity 142 at the base wall 156.

With continued reference to FIG. 3, a bearing housing cover 162 attaches to the connecting column 128 via fasteners 164 to provide a bearing housing for the rolling element bearing 138. A gasket 166 or other sealing material can be interposed between the bearing housing cover 162 and the connecting column 128 to seal the bearing housing. Also, a gasket or lip seal 168 is provided at the top of the bearing housing cover 162 to contain lubricant within the bearing housing during operation of the pump 110 and to isolate grease lubricant for the rolling element bearing 138 from the liquid lubricant in the reservoir 120.

The rolling element bearing 138 is typically lubricated using grease. With reference to FIG. 3, a grease cup 172 communicates with a conduit 174 that extends through the bearing housing cover 162. Through the grease cup 172 and conduit 174 grease lubricant can be introduced into the bearing housing and to the bearing 138. After a period of operation of the pump 110, the bearing 138 needs to be re-lubricated. In the embodiment depicted in FIG. 3, the volume of the cavity 142 of the bearing housing is small. The vertical distance between the lower wall 152 of the bearing 138 (or the horizontal ledge 148) and the base wall 156 of the cavity 142 is approximately 0.25″. Because of the small volume of the cavity 142, very little volume is available for spent grease lubricant. Therefore, to re-lubricate the bearing 138, the pump 110 must be disassembled to remove the spent grease. This requires removal of the pump 110 from the reservoir 120 and complex disassembly and re-assembly of the pump. It is desirable to lengthen the time between re-lubrication cycles.

With reference to FIG. 2, the cavity 42 at the upper end of the connecting column 28 is larger than the known cavity 142 depicted in FIG. 3. In the embodiment depicted in FIG. 2, the distance between the horizontal ledge 48 and the base wall 56 of the cavity is 1.325″. The diameter of the base wall 56 can remain the same as the diameter of the base wall 156 in the known cavity 142, which in the depicted embodiments is 3.25″. Accordingly, the volume of the cavity 42 where the spent lubricant can reside, i.e. a spent lubricant reservoir, is approximately 10.99 cubic inches in the new pump design as compared to the spent lubricant reservoir of the known cavity 142 which is approximately 2.07 cubic inches. This increase in volume of the cavity 42 allows for replenishment of the grease lubricant at specified intervals without disassembly of the pump 10 because the spent lubricant can reside in the cavity 42 below the bearing 38. An increase in the size of the cavity 42 has been found desirable, yet this increase can be achieved by increasing the vertical dimension between the bearing 38 and the base wall 56 of the cavity to any dimension and need not be to the extent described above. The other portions of the cavity 42, for example the upper vertical side wall 44 and the horizontal dimension of the ledge 48 can retain the same dimensions as the known pump 110; however these dimensions can also change should such a change be desirable. Furthermore, the area of the base wall 56 of the cavity 42 could also increase, which would increase the volume of the spent lubricant reservoir. For example, the cavity 42 could take a frustoconical configuration where the lower side wall 44 would be angled so that even more spent lubricant could be accommodated. Many possible configurations exist to increase the size of the cavity 42.

Grease lubricant is introduced into the bearing housing of the new pump 10 in a similar manner as the known pump 110 in that a grease cup 72 communicates with a conduit 74 that extends through the bearing housing cover 62. In the new pump design, the grease cup 72 is located outside the peripheral side wall 24 of the motor support 12. Accordingly, the conduit 74 extends through one of the openings 26 in the motor support 12. This provides a more accessible location for personnel performing grease replenishment. The location of the grease cup 172 in the known pump 110 was adjacent the rotating pump shaft 116 in an area isolated by a guard (not shown). With the conduit 74 being long enough so that the grease cup 72 is located beyond the peripheral side wall 24, a conduit support 76 is provided that rests on and is attached to the cover plate 22. The conduit support 76 can be a piece of angle having a notch that receives the conduit 74.

The new pump design can also include a vent fitting 80 spaced from the conduit 74 and extending through the bearing housing cover 62 to communicate with the cavity 42. The vent fitting 80 allows pressure and excess grease lubricant to escape from the bearing housing while maintaining the integrity of the lip seals 68. The vent fitting 80 can be a form of a one-way valve, e.g. one-way check valve or the like, which allows pressure and excess lubricant to escape while precluding foreign contaminants from entering through the fitting.

The new rotary pump has been described in particular detail, however the invention should not be limited to the specific embodiments discussed above. As just one example, a specific bearing element was described above; however, the invention can be used with other bearing elements. Other modifications and alterations will come to those skilled in the art who have read the preceding description. The invention should only be limited by the appended claims, and the claims should be read to include all modifications and alterations that come within the scope of the claims and the equivalents thereof. 

1. A rotary pump for pumping liquids comprising: a motor; a shaft rotatably driven by the motor; an impeller attached to the shaft; a rolling element bearing at least partially surrounding a portion of the shaft; a bearing housing receiving the rolling element bearing, wherein the bearing housing defines a lubricant reservoir in a volume of the bearing housing not occupied by the rolling element bearing and the lubricant reservoir has a volume greater than 2.25 cubic inches.
 2. The pump of claim 1, further comprising a motor support for supporting the motor.
 3. The pump of claim 2, wherein the motor support includes a peripheral side wall defining an opening.
 4. The pump of claim 3, further comprising a conduit in communication with the bearing housing and a grease cup fitting in communication with the conduit, wherein the conduit extends through the opening in the peripheral side wall of the motor support.
 5. The pump of claim 4, wherein the grease cup fitting is located outside of the peripheral side wall of the motor support.
 6. The pump of claim 5, further comprising a vent in communication with the bearing housing.
 7. The pump of claim 1, further comprising a vent in communication with the bearing housing.
 8. The pump of claim 1, further comprising a connecting column that at least substantially surrounds the shaft.
 9. The pump of claim 8, wherein the connecting column includes a cavity that defines at least a portion of the lubricant reservoir.
 10. The pump of claim 9, wherein the cavity is defined by an at least substantially vertical side wall and a base wall and the rolling element bearing is spaced from the base wall of the cavity at least 0.3 inches.
 11. The pump of claim 10, further comprising a ledge formed in the cavity, wherein the rolling element bearing rests on the ledge and the ledge is spaced at least 0.3 inches from the base wall.
 12. The pump of claim 10, further comprising a ledge formed in the cavity, wherein the rolling element bearing rests on the ledge and the ledge is spaced at least 0.5 inches from the base wall.
 13. The pump of claim 10, further comprising a ledge formed in the cavity, wherein the rolling element bearing rests on the ledge and the ledge is spaced at least 1 inch from the base wall.
 14. The pump of claim 10, further comprising a ledge formed in the cavity, wherein the rolling element bearing rests on the ledge and the ledge is spaced at least 1.325 inches from the base wall.
 15. The pump of claim 1, wherein the lubricant reservoir has a volume greater than 5 cubic inches.
 16. The pump of claim 15, wherein the lubricant reservoir has a volume less than 12 cubic inches.
 17. The pump of claim 1, wherein the lubricant reservoir has a volume greater than 7.5 cubic inches.
 18. The pump of claim 17, wherein the lubricant reservoir has a volume less than 12 cubic inches.
 19. The pump of claim 1, wherein the lubricant reservoir has a volume greater than 10 cubic inches.
 20. The pump of claim 19, wherein the lubricant reservoir has a volume less than 11 cubic inches.
 21. A rotary pump comprising: a rotary shaft adapted to operably connect to a motor; an impeller attached to an end of the rotary shaft; a bearing element at least partially surrounding the rotary shaft; a bearing housing for the bearing element, wherein the bearing element is disposed in the bearing housing; a lubricant conduit through which lubricant can travel toward the bearing element, the lubricant conduit extending through the bearing housing; a vent fitting mounted to the bearing housing, wherein the vent fitting allows at least one of excess pressure and excess lubricant to exit the bearing housing.
 22. The rotary pump of claim 21, wherein the bearing housing defines a volume for storing spent lubricant used to lubricate the bearing element.
 23. The rotary pump of claim 22, wherein the volume for storing spent lubricant is greater than 2.07 cubic inches.
 24. The rotary pump of claim 22, wherein the volume for storing spent lubricant is greater than 3 cubic inches.
 25. The rotary pump of claim 24, wherein the volume of storing spent lubricant is less than 11 cubic inches.
 26. The rotary pump of claim 21, wherein the bearing housing is defined by a base wall that is vertically spaced from the bearing element.
 27. The rotary pump of claim 26, wherein the bearing element is spaced greater than 1.325 inches from the base wall.
 28. The rotary pump of claim 27, wherein the bearing element is spaced greater than 1.5 inches from the base wall.
 29. The rotary pump of claim 28, wherein the bearing element is spaced less than 4 inches from the base wall.
 30. A rotary pump comprising: a motor; a shaft driven by the motor; an impeller driven by the shaft; a motor support upon which the motor rests, the motor support including a peripheral side wall having an opening; a bearing element housing; a bearing element at least partially surrounding the shaft and disposed in the bearing element housing; a conduit attached to the bearing element housing, wherein lubricant can travel through the conduit en route to the bearing element; and a grease cup attached to the conduit, wherein the grease cup is positioned outside the peripheral side wall of the motor support.
 31. The pump of claim 30, further comprising a cover plate attached to the motor support and a conduit support attached to the cover plate. 